Model of Formation of Monodispersed Colloids

Abstract

Ample experimental evidence has been accumulated demonstrating that the formation of monodispersed colloids proceeds through a more complex mechanism, than the generally excepted diffusional "burst nucleation" process. Instead, the synthesis of narrow-size-distribution colloidal dispersions involves several stages, i.e., nuclei produced in a supersaturated solution, grow to nanosize subunits, which then aggregate to form much larger uniform secondary particles. To explain the size selection in such a series of processes, a kinetic model was developed which combined two growth/aggregation stages. This earlier study has shown the burst-nucleation growth of the primary particles to depend strongly on the value of the effective surface tension entering the surface term in the free energy of the subcritical embryos. The aim of the present work has been to identify an appropriate control parameter in the process of secondary particle aggregation. Modifications of the aggregation rates to account for singlet size and aggregate diffusivity produced only small changes. However, introduction of a "bottle-neck" factor in the dimer formation rate had a profound effect on the final size distribution and suggested a possible size-control mechanism.

30 pages in PDF

Cited by in corpus (10)

• Model of nanocrystal formation in solution by burst nucleation and diffusional growth
• Model of Controlled Synthesis of Uniform Colloid Particles: Cadmium Sulfide
• Formation of Monodispersed Cadmium Sulfide Particles by Aggregation of Nanosize Precursors
• Shape Selection in Diffusive Growth of Colloids and Nanoparticles
• Mechanisms of Diffusional Nucleation of Nanocrystals and Their Self-Assembly into Uniform Colloids
• Morphology of Fine-Particle Monolayers Deposited on Nanopatterned Substrates
• Models of Synthesis of Uniform Colloids and Nanocrystals
• Synthesis of Dispersed Metal Particles for Applications in Photovoltaics, Catalysis, and Electronics
• Computational model for the formation of uniform silver spheres by aggregation of nanosize precursors
• Synthesis of Silver Colloids: Experiment and Computational Model